1. Field of the Invention
This invention relates to a method for recovering metal from metal oxide, and more specifically, this invention relates to a method for producing metal powder from metal oxide without the production of waste, nor the need to recondition reaction liquor.
2. Background of the Invention
The recent renewed interest in nuclear power stems from higher petroleum costs and also petroleum's role in carbon dioxide emissions. According to the Intergovernmental Panel on Climate Change (IPCC), total carbon emissions from the energy sector are expected to grow from today's 6.5 billion tons to 13 billion tons in 2050, with total cumulative emissions of carbon through 2050 of 440 billion tons.
The management of a nuclear system of a scope to even begin ameliorizing this anticipated carbon load requires planning. For example, a worldwide capacity of 3500 GWe (a figure of illustrative convenience, ten times current capacity), if based on a once-through fuel cycle using light water reactors, would generate roughly 700 tons of plutonium annually, and would require on the order of one-half million tons of natural uranium annually. If based on liquid-metal plutonium breeder reactors, it would involve the fabrication into fresh fuel annually of over five thousand tons of plutonium. Such a quantity of plutonium exacerbates the potential of its diversion for military and paramilitary purposes.
Also, efforts are ongoing to extend the life of currently operating nuclear reactors and introduce successive generations of more advanced reactors to the U.S. energy infrastructure. As the number of deployed nuclear reactors increase, the demands of a once-through fuel cycle paradigm on long-term repositories also increase.
Ninety percent of the waste proposed for disposal at the geologic repositories generally consists of spent nuclear fuel, such as that generated by commercial nuclear power plants, government reactors, and naval-propulsion-plant reactors. A large portion of spent nuclear fuel consists of certain metal oxides, such as plutonium oxide, uranium oxide, and zirconium oxide. The volume of these oxides must be minimized.
U.S. Pat. No. 4,399,108, awarded to Krikorian et al. on Aug. 16, 1983, discloses a catalyst/molten metal combination for reprocessing spent nuclear fuels.
U.S. Pat. No. 4,740,359 awarded to Haid Ali et al. On Apr. 26, 1988, discloses an organic/aqueous extraction method for reprocessing nuclear fuels.
U.S. Pat. No. 2,813,019, awarded to Olson on Nov. 12, 1957, discloses a method for producing zirconium metal via the reduction of zirconium halides using reducing metals.
U.S. Pat. No. 4,923,577, awarded to McLaughlin et al. on May 8, 1990, discloses a method for reducing zirconium chloride via treatment in a bath containing alkali metal chlorides and alkaline metal chlorides.
None of the aforementioned prior art teaches a method for reducing metal oxides found in spent nuclear fuel which features in situ rejuvenation of reducing agent. Further, none of the aforementioned prior art teaches a continuous reducing process of metal oxides, whereby the only limiting reagent is the feedstock metal oxide.
A need exists in the art for a method for recovering metals from spent nuclear fuel. The method should eliminate the need for recharging of reduction baths. The method should also allow for the continuous processing of metal oxides such that the only significant limiting reagent is the metal oxide.